595
FXUS62 KKEY 110008
AFDKEY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
808 PM EDT SAT OCT 10 2026
..NEW UPDATE, AVIATION
KEY MESSAGES
- A COASTAL FLOOD STATEMENT REMAINS IN EFFECT, AND PARTICULARLY
LOW LYING AREAS WILL SEE SOME SALTWATER PONDING AROUND THE TIMES
OF HIGH TIDE.
- WESTERLY SWELL GENERATED BY POST-TROPICAL CYCLONE ISAIAS WILL
GRADUALLY SUBSIDE ACROSS THE WESTERN HALF OF THE COASTAL WATERS
THIS EVENING.
- ELEVATED RAIN CHANCES ARE EXPECTED TONIGHT. SHOWER CHANCES WILL
DECREASE DURING THE REMAINDER OF THE HOLIDAY WEEKEND.
UPDATE
ISSUED AT 752 PM EDT SAT OCT 10 2026
DESPITE DEEP MOISTURE IN PLACE WITH PWATS IN EXCESS OF 2 INCHES
AREA-WIDE, RECENT KBYX RADAR IMAGERY JUST SHOWS SCATTERED SHOWERS
AND A FEW EMBEDDED STORMS MOVING TO THE NNW ACROSS THE STRAITS
THIS EVENING. THE TROPICAL MOISTURE CONTINUES TO FEED INTO THE
REGION BETWEEN THE REMNANT CIRCULATION OF ISAIAS IN THE TN VALLEY
AND MID/UPPER LEVEL RIDGING CENTERED TO THE SW OF BERMUDA. LATEST
HI-RES GUIDANCE CONTINUES TO SUGGEST THAT PRECIPITATION COVERAGE
WILL INCREASE LATER THIS EVENING AND OVERNIGHT WITH SCATTERED TO
OCCASIONAL NUMEROUS SHOWERS AND OCCASIONAL STORMS DRIFTING
NORTHWESTWARD ACROSS THE REGION. WITH THE ATLANTIC RIDGE BUILDING
IN FROM THE WEST OVERNIGHT AND HEIGHTS ALOFT SLIGHTLY INCREASING,
OVERALL FORCING FOR ASCENT ALOFT WILL BE LACKING. HOWEVER, THE
RIDGE BUILDING IN FROM THE WEST WILL ALSO BRING A MUCH DRIER AIR
MASS INTO THE REGION WITH PWATS POSSIBLY FALLING AS LOW AS 1.5
INCHES INTO SUNDAY. AS THE LEADING EDGE OF THIS DRIER AIR MASS
APPROACHES THE REGION OVERNIGHT INTO SUNDAY MORNING, THE LOW-LEVEL
FLOW WILL BECOME INCREASINGLY MORE SOUTHEASTERLY AND THIS SHOULD
FAVOR SPEED CONVERGENCE PRECIPITATION DEVELOPMENT, WHICH WILL BE
FURTHER ENHANCED ALONG AND AHEAD OF THE BOUNDARY OF THE DRY AIR
MASS. THUS, DESPITE THE LACK OF ANY MEANINGFUL FORCING ALOFT,
THERE SHOULD STILL BE ENOUGH LIFTING MECHANISMS IN PLACE TO KEEP
CHANCE/LIKELY POPS FOR THE OVERNIGHT PERIOD SO WILL MAINTAIN
INHERITED FORECAST REASONING FROM EARLIER IN THE DAY. OTHERWISE,
EXPECT ANOTHER WARM AND HUMID SATURDAY NIGHT ACROSS THE FLORIDA
KEYS WITH LOWS IN THE LOWER 80S AND DEWPOINTS IN THE UPPER 70S.
DISCUSSION
ISSUED AT 225 PM EDT SAT OCT 10 2026
WEATHER ACROSS THE FLORIDA KEYS TURNED OUT TO BE SURPRISINGLY
UNEVENTFUL THIS SATURDAY. SHOWER DEVELOPMENT WAS LIMITED TO THE
OUTER GULF WATERS AND THE WESTERN WATERS OF THE FLORIDA STRAITS.
MEANWHILE, THE MORNING SOUNDING SAMPLED A DAILY RECORD PWAT VALUE
ABOVE 2.3 INCHES. SATELLITE OBSERVATIONS FROM CIMSS-MIMIC
ESTIMATED MOISTURE TOTALS CLOSER TO 2.1 TO 2.2 INCHES THIS
MORNING. HOWEVER, IF ONE LOOKS OUTDOORS THE ATMOSPHERE DOES NOT
APPEAR VERY SATURATED. CLOUDS ARE STRUGGLING TO FORM ACROSS THE
EASTERN WATERS SURROUNDING THE KEYS, AND THE KBYX RADAR DETECTED
SPARSE SHOWER ACTIVITY, IF ANY, EAST OF THE LOWER KEYS EARLIER
TODAY. DEW POINTS IN THE UPPER 70S INDICATE MORE THAN ENOUGH
MOISTURE IS PRESENT FOR WIDESPREAD SHOWERS. WHY HAS SHOWER
COVERAGE BEEN SO SPARSE?
LOW LEVEL WINDS ARE LIKELY THE REASON WE HAVE SEEN A LACK OF
SHOWER ACTIVITY. MODERATE TO FRESH SOUTHERLY BREEZES WERE PRESENT
ACROSS THE WESTERN STRAITS THIS MORNING WHILE GENTLE TO MODERATE
SOUTHEASTERLY TO SOUTH BREEZES WERE OBSERVED ALONG THE REEF. THIS
RESULTED IN A REGION OF LOW LEVEL DIVERGENCE ACROSS THE KEYS,
EXCEPT FOR WHERE WINDS WERE ACCELERATING OVER THE OUTER GULF.
HOWEVER, AS WHAT USED TO BE HURRICANE ISAIAS MOVES FURTHER NORTH
INTO THE SOUTHEASTERN UNITED STATES, BREEZES ARE ON TRACK TO
SLACKEN AND BACK SOUTHEASTERLY. EVEN THOUGH MORE THAN ENOUGH
MOISTURE IS PRESENT, IT IS LIKELY SHOWERS WILL STRUGGLE TO FORM
UNTIL WINDS SHIFT FURTHER TO THE SOUTHEAST. THE MOST RECENT
STATISTICAL GUIDANCE SUGGESTS THE WIND SHIFT WILL OCCUR AFTER
SUNSET. TONIGHT, WE ARE FORECASTING THAT SHOWER COVERAGE WILL
INCREASE WHILE WINDS SLACKEN AND BACK TO GENTLE TO MODERATE
SOUTHEASTERLY BREEZES.
LOOKING AHEAD, THERE ARE A FEW FEATURES OF INTEREST. A TROPICAL
UPPER TROPOSPHERIC TROUGH IS STILL SPINNING SOUTH OF CUBA. POST-
TROPICAL CYCLONE ISAIAS IS BEING ABSORBED INTO THE MID-LATITUDE
FLOW FIELD OVER THE SOUTHEASTERN US. THERE ARE ALSO TWO REGIONS OF
HIGH PRESSURE; ONE IS LOCATED OVER SOUTHEASTERN TEXAS, WHILE THE
OTHER IS BEGINNING TO MOVE INTO THE NORTH ATLANTIC FROM NEW
ENGLAND. OVER THE REMAINDER OF THE WEEKEND, ISAIAS IS ON TRACK TO
FULLY TRANSITION INTO A MID-LATITUDE SYSTEM WITH A FRONT EXTENDING
SOUTH TOWARDS SOUTH FLORIDA. THE HIGH OVER TEXAS WILL BE
SUFFICIENT TO PUSH THE FRONT OVER THE GULF AND TOWARDS THE KEYS.
MEANWHILE, THE ATLANTIC HIGH WILL BE ABLE TO BUILD AND MAINTAIN
SOUTHEASTERLY BREEZES THROUGH TOMORROW. THE MAIN SOURCE OF
UNCERTAINTY STEMS FROM WHAT HAPPENS TO THE AFOREMENTIONED FRONT.
STATISTICAL MODELS SUGGEST IT WILL PASS ACROSS THE FLORIDA KEYS BY
MID-WEEK. THE CHALLENGE STEMS FROM WHAT HAPPENS TO THE WINDS AND
THE DEW POINTS. WILL DEW POINTS BE ABLE TO DECREASE TO NEAR 70, OR
EVEN THE UPPER 60S? IF SO, HOW LONG WILL THAT LAST? WILL THERE BE
A DISTINCT WIND SHIFT AND SURGE IN WIND SPEED? THESE QUESTIONS
WILL BECOME MORE CLEAR BY THE END OF THE HOLIDAY WEEKEND. AT THE
VERY LEAST, THE NEXT COUPLE OF DAYS WILL BE FREE OF NEARBY
TROPICAL CYCLONES.
MARINE
ISSUED AT 225 PM EDT SAT OCT 10 2026
NO WATCHES, WARNINGS, OR ADVISORIES ARE IN EFFECT FOR THE
NEARSHORE OR OFFSHORE WATERS OF THE FLORIDA KEYS.
FROM SYNOPSIS: ENHANCED SWELLS GENERATED BY POST-TROPIAL CYCLONE
ISAIAS ARE STEADILY SUBSIDING ACROSS THE WESTERN WATERS OF THE
FLORIDA KEYS. BREEZES ARE SLOWLY SLACKENING TO GENTLE TO MODERATE
BREEZES THIS WEEKEND. SHOWER COVERAGE WILL START TO INCREASE
TONIGHT AS BREEZES BACK SOUTHEASTERLY TO EASTERLY. DURING THE
SECOND HALF OF THE WEEKEND, BREEZES ARE ON TRACK TO BACK FURTHER
NORTHEASTERLY. DRIER AIR WILL START TO FILTER IN ON SUNDAY, AND
SHOWER CHANCES WILL DROP BELOW NORMAL BY THE START OF THE WORK
WEEK. A FRONTAL BOUNDARY ASSOCIATED WITH POST-TROPICAL CYCLONE
ISAIAS MAY PUSH THROUGH THE FLORIDA KEYS MID-WEEK.
AVIATION
(18Z TAFS)
ISSUED AT 650 PM EDT SAT OCT 10 2026
SCATTERED SHRA AND EMBEDDED TSRA ARE EXPECTED TO PUSH NORTHWARD
ACROSS THE REGION LATER THIS EVENING AND INTO THE OVERNIGHT HOURS,
BUT OVERALL CONFIDENCE IN COVERAGE AND TIMING IS LOW AT THIS TIME.
THUS, HAVE ADDED VCSH TO BOTH KEYW AND KMTH THROUGH AROUND 10Z
SUNDAY WITH MAINLY DRY CONDITIONS THEN EXPECTED THROUGHOUT THE DAY
TOMORROW. OTHER THAN SOME POSSIBLE BRIEF VSBY RESTRICTIONS DURING
THE PRECIPITATION ACTIVITY, VFR CONDITIONS WILL PRIMARILY PREVAIL
WITH SE WINDS OVERNIGHT AND GRADUALLY BECOMING MORE EASTERLY BY
SUNDAY EVENING WITH WIND SPEEDS AROUND 10 KTS AND OCCASIONAL
HIGHER GUSTS.
CLIMATE
ON THIS DAY ON 2009, THE DAILY RECORD WARM LOW TEMPERATURE OF 84F
WAS RECORDED IN KEY WEST. TEMPERATURE RECORDS FOR KEY WEST DATE
BACK TO 1872. ALSO, ON THIS DAY IN 1975, THE DAILY RECORD WARM LOW
TEMPERATURE OF 83F WAS RECORDED IN MARATHON. TEMPERATURE RECORDS
FOR MARATHON DATE BACK TO 1951.
KEY WATCHES/WARNINGS/ADVISORIES
FL...NONE.
GM...NONE.
PUBLIC/MARINE/FIRE...RG
AVIATION/NOWCASTS....RG
DATA ACQUISITION.....DR
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